1. Field of The Invention
The invention relates to a method of cleaning the outer surface of a cylinder in an offset printing press, such as a blanket cylinder, an impression cylinder, a plate cylinder, or an inking cylinder. More particularly, the invention relates to a method of cleaning the outer surface of a cylinder by using a cleaning fabric intermittently or continuously fed from a supply, and engaged with and pressed against the outer surface of the cylinder.
2. Description of Related Art
There has been generally used a device for cleaning the outer surface of a cylinder in an offset printing press, as disclosed in U.S. Pat. No. 4,344,361. The device comprises an expandable pad opposed to the outer surface of the cylinder and mounted on a frame. A cleaning fabric is directed to a take-up roll from a supply roll through the pad. The take-up roll is intermittently rotated to take up the cleaning fabric so that the cleaning fabric is intermittently fed to the pad from the supply roll. The cleaning fabric is intermittently engaged with and pressed against the outer surface of the cylinder by the pad which is inflated by air under pressure whenever the cleaning fabric is intermittently fed, to clean the outer surface of the cylinder. The cleaning fabric is nipped between the pad and the cylinder within a stripe range having a nip width in the feeding direction of the cleaning fabric.
In the device, it is customary that the cleaning fabric is engaged with the outer surface of the cylinder for a constant period a time, throughout a cleaning cycle for accomplishing the cleaning of a cylinder. In addition, the cleaning fabric is fed for a length a time which corresponds to the nip width of the cleaning fabric, throughout the cleaning cycle. For example, the cleaning fabric is nipped between the pad and the cylinder within a stripe range having a nip width of about 5 to 8 mm. Accordingly, the cleaning fabric is fed for a length of about 5 to 8 mm every three rotations of the cylinder. The cleaning fabric is fed twenty times in the cleaning cycle so that it consumes the cleaning fabric of about 100 to 160 mm. The used fabric is then taken up about the take-up roll for disposal.
By the way, the cylinder is made clean more and more in accordance with the progress of cleaning toward the end of the cleaning cycle. Accordingly, the cleaning fabric is made heavily dirty and saturated with dirt only at the beginning of the cleaning cycle. The cleaning fabric gradually decreases in degree of the dirt in accordance with the progress of cleaning toward the end of the cleaning cycle. As to the latter half in length of the cleaning fabric used in the cleaning cycle, it is little dirty and still available to clean the outer surface of the cylinder. Accordingly, it is wasteful of cleaning fabric to dispose it in spite of the availability thereof.
There has been also used a device for cleaning the outer surface of a cylinder in an offset printing press, in which the cleaning fabric is not intermittently but continuously fed from a supply, and engaged with and pressed against the outer surface of the cylinder to clean the outer surface of the cylinder. In the device, it is customary that the cleaning fabric is fed at a constant speed, throughout the cleaning cycle. Accordingly, the used fabric includes a substantial portion which is little dirty and still available to clean the outer surface of the cylinder. It is wasteful of cleaning fabric to dispose it in spite of the availability thereof.
In addition, there has been heretofore proposed a cleaning fabric which has a cleaning agent or detergent previously impregnated thereinto, as disclosed in U.S. Pat. No. 5,368,157. The cleaning fabric may alternatively have a cleaning agent or detergent in the form of jelly or paste applied onto the cleaning fabric. A cleaning agent or detergent may be received in a receptacle which is mounted on the printing press so that the cleaning fabric is directed into the receptacle from the supply roll and then fed to the pad. The cleaning agent or detergent is impregnated into the cleaning fabric when the cleaning fabric is directed into the receptacle. The cleaning agent or detergent may be sprayed onto and impregnated into the cleaning fabric by nozzles mounted on the printing press, as disclosed in U.S. Pat. No. 4,344,361. In the cases, it is wasteful of not only cleaning fabric but also cleaning agent or detergent to dispose it in spite of the availability thereof.
It is therefore an object of the invention to provide a new and improved method of cleaning the outer surface of a cylinder by using a cleaning fabric intermittently or continuously fed from a supply, and engaged with and pressed against the outer surface of the cylinder, to thereby overcome the above problems.
Another object of the invention is to eliminate the waste of cleaning fabric.
Other object of the invention is to eliminate the waste of not only cleaning fabric but also cleaning agent or detergent.